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Gtir Motorsport club » Tech room » Help and Advice » Compression test results

Compression test results

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1 Compression test results on 12th March 2019, 1:16 pm

mike74

mike74
Yip, my turn now. I just did the test and got the following results:
Cyl 1 150psi
Cyl 2 150 psi
Cyl 3 130 psi
Cyl 4 150
Cyl 3 wet test about 143 psi

Anything here to worry about or anything else i can do?
The car still seems to blow smoke (per another thread) at WOT but, not each and every time. I was thinking it could be turbo or worn rings maybe? Its used about 1/4 litre oil in the past month or 1000 miles or so, so not too excessive.

Turbo had no axial play BUT about 1mm radial play in it.
The smoke issue seems to be worse when its cold outside, like in the morning. On the way home yesterday evening it was fine! Really starting to piss me off now as ive tried everything i can think on...not even entirely sure what colour smoke is! Tail pipe is sooty and not oily and plugs are bone dry with a dark tea colour on their tips. All plugs look exactly the same too.

Please help before i do an insurance job on it!!!!!

Cheers,
Mike

2 Re: Compression test results on 12th March 2019, 1:35 pm

mike74

mike74
Okay on closer inspection theres a bit more build up on plug 3 Sad

3 Re: Compression test results on 12th March 2019, 2:11 pm

DC313

DC313
Id say 1mm of radial play in the turbo shaft is acceptable, what are all your boost lines / intercooler internals like, any Oil in them?

4 Re: Compression test results on 12th March 2019, 2:19 pm

mike74

mike74
A bit of oil but nothing excessive

5 Re: Compression test results on 12th March 2019, 2:37 pm

DC313

DC313
Hmm tricky, on cold mornings cars always smoke abit more than normal, be better if you can see what colour smoke it is, any tapping from the engine? thinking something valve related to?

6 Re: Compression test results on 12th March 2019, 2:43 pm

mike74

mike74
Apart from the intermittent smoke the engine seems fine. No nasty rattles, knocking or anything else. Pulls really well too

7 Re: Compression test results on 12th March 2019, 9:00 pm

Mr B

Mr B
gtir technician
gtir technician
cylinder 3 popular one have issues, ringlands is the common one,
exhuast valve troubles do happen from worn guides, stem seals and could also be seating bad thus lower reading .
The difference in your test shows it got some issues, need leak down test and stick a bore scope down it .
Turbo radial play about 0.3 - 0.6mm is roughly what you see on a dial gauge pending on exact turbo bearing assembly in question, assume you blade not able touch housing if loaded on one side .
You don't need extra play for leaks as oil pressure out of spec and issue right at the seal could result in oil bypass even on a in spec clearance assembly .
pulling exhaust manifold off can be useful at looking at oil leaking from bad exhaust valve and inspecting turbo closer .

8 Re: Compression test results on 12th March 2019, 9:14 pm

johnny gtir

johnny gtir
moderator
moderator
Plug 3 looks different to the rest to me which backs up suspect and readings

9 Re: Compression test results on 12th March 2019, 9:36 pm

mike74

mike74
I think plug 3 in the picture looked worse than it actually was. All the plugs had deposits on them, presumably from just having run a bottle of cleaner through the last tank.
Even though i still want to cry. Im thinking about letting cylinder 3 soak in something this weekend to hopefully free off the rings. If that fails its either getting set on fire or sold Sad

10 Re: Compression test results on 12th March 2019, 9:48 pm

Mr B

Mr B
gtir technician
gtir technician
man up and fix it, if is valve related it simple head off refurb .
If was piston ring land as long bore decent enough it is possible refurb that with engine left in and for pretty small money .

11 Re: Compression test results on 12th March 2019, 10:02 pm

mike74

mike74
I think theres possibly a bore scope kicking around at my work...will ask tomorrow and put on my best sad puppy dog face!
Fwiw i didnt see any signs of oil on exhaust ports when id the turbo off last year and it was smoking back then too. The turbo impellor doesnt touch the housing either...

12 Re: Compression test results on 12th March 2019, 10:47 pm

Mr B

Mr B
gtir technician
gtir technician
from your wet test i would assume piston/rings .
is pretty common occurrence on well used R on standard pistons, more so when had some fuelling issues for some time .

13 Re: Compression test results on 14th March 2019, 2:34 pm

mike74

mike74
Ok, so we bore scoped cylinders 2+3 not long ago. The bore of no. 3 was fine. There was a few very light scratches but nothing to indicate anything insidious, just marks as you'd expect to find in an older engine. In fact my mate said he could actually see the original honing marks still present! There was an oily/carbon deposit on the piston crown though. He suggested we then look at no. 2 to compare. To my horror no. 2 had the same oily/carbon crap on top! There seemed to be more of this crap along with some ash (?) underneath the exhaust valves on both these cylinders.

He reckoned that the rings are actually fine, given the lack of any damage to the cylinders. He actually reckoned that the valve guides are probably worn and not letting the valves shut n seal correctly; hence lack of compression and smoke. Either that or someone's fooked up shimming the valves in the past so some aren't closing properly.

I've now ordered up a leak down tester so hopefully that will definitively show where the fook all my compression is going.

Watch this space...

14 Re: Compression test results on 14th March 2019, 7:16 pm

Mr B

Mr B
gtir technician
gtir technician
Hopefully it is head as easier/cheaper fix.
valve guide wear and seals gone hard is common on exhaust valves .
redo your compression and wet test and that mixed with good leak down test may draw conclusive direction.
I have seen fooked ringlands/rings and good bores more than once though .
Bore scope with mirror attachment good as can set valves open and get view seat and see evidence of oil bypass all without having head on a bench .
good luck ...

15 Re: Compression test results on 14th March 2019, 8:43 pm

mike74

mike74
Yeah fingers crossed. Should have a diagnosis in a week all being well. Swapping a head over is a much easier pill to swallow than a piston or a whole engine though

16 Re: Compression test results on 14th March 2019, 8:45 pm

mike74

mike74
Quick question; IF it was a bad ring, wouldnt it smoke all the time rather than every other time? On way home tonight there was no smoke again...

17 Re: Compression test results on 14th March 2019, 8:54 pm

Mr B

Mr B
gtir technician
gtir technician
yeh your smoke at warm ups tends favour leaking valve stems .
pending on what exactly wrong with a cylinder/piston/rings it could be worse when cold .
Did you wet test other cylinders as a baseline to difference between dry and wet test on good and bad cylinders .
One can hope it is the head but you want good diagnostic data prior a head off and physical evidence of valve sealing once head off to not pull pistons, nothing worse than doing top end and putting it back together with piston issue .
proper leakdown test and head off inspection probably have it diagnosed 100% and fixed pretty easily probably .

18 Re: Compression test results on 14th March 2019, 10:16 pm

mike74

mike74
Nah i only wet tested no.3 cylinder. When i do the leak down test next week ill redo the compression test with a little oil.
Ill report back then, hopefully with good news! Cheers for the help and kick up the backside buddy Smile

19 Re: Compression test results on 15th March 2019, 12:16 am

Mr B

Mr B
gtir technician
gtir technician
Top end overhaul be well worth doing and if not got ported manifold or 3" elbow would be time consider adding it perhaps .
Stay positive, pretty trivial issues and if you can wrench yourself really not overly expensive or too much down time and fun too if your scottish weather not too miserable :-S
amazes me how many owners sell up a decent R yet keep a right rough wife haha :-) best wishes ...

20 Re: Compression test results on 15th March 2019, 7:42 am

DC313

DC313
Sounding positive (Ish) Keep us updated with progress and fingeres crossed it is a valve seal!

21 Re: Compression test results on 19th March 2019, 1:54 pm

mike74

mike74
Right, I'm slightly confused but, relieved at the same time.
We just re-did compression tests and also leak down tests.
cylinders 1 & 2: 160psi
cylinders 3 & 4: 150psi
Leak down tests showed nothing leaking anywhere that it shouldn't!
The tests were done when the engine was really hot this time as last week it had probably sat cooling down for half an hour ish before testing (engine still felt hot though).
It would appear that the valves and rings are actually ok (phew!!!)
My mate reckoned that since I have the kit to check this that I re-do the tests periodically to see if anything changes. He reckoned also that if there was anything up with it, it was more likely a valve issue than anything else.
So no closer than before as to why this fricking car periodically smokes like Bob Marley.
I've got a new crank damper on order as mine has seen better days so i'll re-check the ignition timing after I fit it just in case somethings moved. After that I really don't know as I've changed pretty much everything apart from injectors...still at least the engine's not fucked Very Happy

22 Re: Compression test results on 19th March 2019, 6:56 pm

johnny gtir

johnny gtir
moderator
moderator
Remind me again what breather set up you running what oil etc mate

23 Re: Compression test results on 19th March 2019, 8:42 pm

mike74

mike74
10w50 synthetic oil and crank and cam case breathing to atmoshpere

24 Re: Compression test results on 19th March 2019, 9:09 pm

Mr B

Mr B
gtir technician
gtir technician
i'm a big fan of the standard breather setup in good order/uprated .
I would be checking for valve stem seals leaking as even without lot of guide wear the exhaust go hard and can leak while car resting and cause smokey running until burn what on valve and piston off .
pulling plugs sometimes allows you see oil drops on pistons, good bore scope which has mirror attachment or twisting head control allows you view valves for signs of oil, pulling exhaust manifold also good way get evidence on valve seal leaking .
Wouldn't rule out the turbo at this stage either if cylinder comp tests prove good, more looking and testing needed,

25 Re: Compression test results on 20th March 2019, 8:49 am

mike74

mike74
Yeah, that's kinda what i'm thinking too Mr B. I might be able to unbolt the exhaust manifold and pull it away from the head just enough to have a look at the exhaust ports.

I fitted the standard FPR back on to it last night just to rule out the aftermarket one I had on. Its maybe just my imagination but I think its running a bit better than before.
I had a major blond moment when I tried to start it after fitting it though...it would start and run rough as fook for a few seconds then die. I assumed it was maybe still a little air in the fuel rail so tried a few more times. Same results. It was only when I went round to the front of the car I realised I hadn't put the intercooler back on!! Twat!

I've got new inlet manifold, plenum and IACV gaskets on order so I'll fit them when I can, just to further rule out any inlet tract leaks. Everything else on the inlet side has been checked and replaced so the gaskets are the only original items left there now.
If that fails then I guess it can only be the turbo or valve seals. Watch this space and I'll update when I can.

cheers for the help though guys Very Happy

mike

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